SESI Learning Series: 75th Percentile Evaluation An Economical Solution to Disposal
February 10, 2016

Do you have environmentally impacted soil that you need to dispose of? Do you want to be paid to import fill to your site? Before making a disposal or import decision, you should know the most up­to­date NJDEP Guidance. The NJDEP has developed the "Fill Material Guidance for SRP Sites," updated April 2015 and referenced herein as "the Guidance." The Guidance outlines approved alternative fill types, testing procedures, etc. for materials intended for use at sites that are in the Site Remediation Program (SRP). In addition, the Guidance provides a procedure for assessing the use of environmentally impacted soil from off­site sources as an alternative fill. This procedure is known as the 75th Percentile Evaluation.

The 75th Percentile Evaluation is a tool that the NJDEP has developed that has huge potential as an economical disposal solution for the environmental community. Unfortunately, the Guidance is fairly new and the development community may not know much about it, are not taking advantage of it due to the additional analysis required, and/or don't realize the economic potential for the tool. The concept is fairly simple:

1. An area of concern (AOC), whether isolated or site­wide, is identified at the receiving SRP site;
2. The statistical 75th percentile concentration for all samples for a given contaminant is calculated from existing testing data and based on a formula provided in the Guidance; and,
3. Once the 75th percentile concentration has been determined for a site, then potential import sources can be evaluated. The import fill sources may only contain contaminants that are similar to what exist on the receiving site ("like­on­like" requirement), with maximum concentrations for each contaminant below the 75th percentile concentration. In addition, testing of the import fill sources must typically performed in accordance with the Guidance.

The 75th Percentile Evaluation can be used by developers to offset construction costs on SRP projects that require fill by charging a fee for the disposal of contaminated soils meeting the "like­on­like" disposal requirement. Simultaneously the cost of buying the fill can be deducted from the project budget. The Guidance also economically benefits the donor site because the fee for disposal on an SRP site can be negotiated to be much less than landfill disposal. In addition, trucking costs to a landfill can also be deducted if the SRP receiving site is close to the donor site. The proliferation of the use of this evaluation is highly dependent upon developers and consultants understanding the process and the potential cost impact. In addition, it requires the environmental community to work together to identify potential contaminant­ based disposal sites.

SESI's environmental team can assist you with all of phases of environmental engineering and evaluation including the 75th Percentile Evaluation, sampling and analyses of fill, and review and coordination for fill disposal. We are well versed in the new NJDEP Site Remediation Program and we have two Licensed Site Remediation Professionals (LSRP) on staff.

For more information on the 75th Percentile Evaluation and your other environmental needs please contact Justin Protasiewicz at 973­-808­-9050.

*Information based on regulations as of 2/10/16